でーす

is, am, are

→ だ
auxiliary · informal Rare #26,438
is, am, are A playful, drawn-out spelling of polite です; often sounds cheerful or casual.
JA: ここが入口でーす。
EN: This is the entrance.
Conjugation of だ

宅配でーす

Delivery!

— Arrietty (2010)

今は大丈夫でーす

I'm good for now.

— 崖の上のポニョ (2008)

うるさいでーす

You're so annoying!

— 万引き家族 (2018)

よろしくでーす

Nice to meet you!

— One Cut of the Dead (2017)

担任のキタノでーす

I’m your homeroom teacher, Mr. Kitano!

— バトル・ロワイアル (2000)

お疲れさまでーす

Thanks for your hard work!

— One Cut of the Dead (2017)

死んだ順番でーす

This is the order in which they died.

— バトル・ロワイアル (2000)